CN109964297B

CN109964297B - Vacuum switching device and electrical contact therefor

Info

Publication number: CN109964297B
Application number: CN201780070208.2A
Authority: CN
Inventors: W·李; 余砾; S·R·马图
Original assignee: Eaton Intelligent Power Ltd
Current assignee: Eaton Intelligent Power Ltd
Priority date: 2016-11-21
Filing date: 2017-11-13
Publication date: 2021-11-02
Anticipated expiration: 2037-11-13
Also published as: US20180151307A1; US9922777B1; CN109964297A; WO2018093704A1; US10490363B2; EP3542387B1; EP3542387A1

Abstract

The invention provides an electrical contact (100, 200) for a vacuum switching apparatus. The vacuum switching device (2) comprises a second electrical contact. The electrical contact (100) includes a central portion (102) and a plurality of lobe portions (110, 120, 130, 140) each extending from the central portion. Each of the plurality of petal portions has a first surface (112, 132, 152, 172) and a second surface (114, 134, 154, 174). The first surface (112, 132, 152, 172) faces a first direction and is configured to engage with a second electrical contact (200). The second surface faces a second direction generally opposite the first direction. At least one of the plurality of petal portions also has a trough-like portion (116, 136, 156, 176) extending inwardly from the second surface toward the first surface.

Description

Vacuum switching device and electrical contact therefor

Cross Reference to Related Applications

This patent application claims priority to and benefit from U.S. patent application serial No. 15/357,148, filed on 21/11/2016, which is incorporated herein by reference.

Background

Technical Field

The disclosed concept relates to vacuum switching apparatus, such as, for example, vacuum switches comprising a vacuum envelope, such as, for example, vacuum circuit breakers. The disclosed concept also relates to an electrical contact for a vacuum circuit breaker.

Background

The vacuum interrupter includes separable main contacts located within an insulated, hermetically sealed vacuum chamber. The vacuum chamber typically includes, for example, but is not limited to, a plurality of ceramic segments (e.g., without limitation, a plurality of tubular ceramic portions) for electrical insulation that are terminated by a plurality of end members (e.g., without limitation, metal components such as metal end plates, end caps, sealing cups) to form an enclosure of an extractable partial vacuum. The exemplary ceramic segment is generally cylindrical; however, other suitable cross-sectional shapes may be used. Two end members are typically employed. Where there are multiple ceramic segments, an inner center shroud is disposed between these exemplary ceramic segments. Some known vacuum interrupters include a radial magnetic field generating mechanism, such as, but not limited to, a spiral electrical contact or an end cup, which is designed to force the arc column to rotate between a pair of electrical contacts that interrupt high currents, thereby spreading the arc load over a relatively wide area. These vacuum interrupters have a number of disadvantages. For example, electrical contacts are typically subjected to a large number of mechanical operating cycles at high speeds and forces. Both the force and velocity contribute to the momentum and impact energy of the electrical contacts during opening and closing. For faster separation between the electrical contacts, a high opening speed is desirable to aid in dielectric recovery strength between the electrical contacts. When the electrical contacts close to each other under voltage, high closing speeds are desirable to minimize pre-strike arcing and subsequent welding. High voltages require high speeds and high currents require high forces.

When the opening and/or closing speed is high and the contact force on closing is large to the extent required for high fault currents, the individual petals of the electrical contact often undesirably break and open from the rest of the electrical contact. Known remedies to prevent premature failure of the petals include making the electrical contacts thicker, machining the peripheral portion of the electrical contact sheet by tapering the electrical contacts on one or both sides, and adding mechanical supports on the underside of the petals. Making the electrical contacts thicker increases the cost of the contact material and also results in no high concentration of current towards the arc surface, thereby reducing the transverse magnetic field. Tapering the electrical contact limits the maximum value of the radius of the edge on the outer diameter of the electrical contact, thereby adversely affecting the dielectric properties of the contact. Finally, the addition of mechanical supports not only increases the cost of the vacuum interrupter, but also complicates design and manufacture. More specifically, if the support is not mechanically joined (e.g., via brazing) to the petals, it will only minimize the bending of the petals in a direction toward the support, but not in the opposite direction away from the support. If the support member is mechanically engaged to the petals, unless a cut is also made into the support member, the support member will electrically bridge the slot machined into the electrical contact, a process that will undesirably weaken the mechanical strength of the support member.

There is therefore room for improvement in vacuum switching apparatus and in the electrical contacts thereof.

Disclosure of Invention

These needs and others are met by embodiments of the disclosed concept, which relate to vacuum switching apparatus and electrical contacts therefor.

According to one aspect of the disclosed concept, an electrical contact for a vacuum switching apparatus is provided. The vacuum switching apparatus includes electrical contacts. The electrical contact includes a central portion and lobe portions each extending from the central portion. Each of the plurality of petal portions has a first surface and a second surface. The first surface faces a first direction and is configured to engage a second electrical contact. The second surface faces a second direction generally opposite the first direction. At least one of the plurality of petal portions also has a trough-like portion extending inwardly from the second surface toward the first surface.

As another aspect of the disclosed concept, a vacuum switching apparatus is provided that includes the aforementioned electrical contacts.

Drawings

A full appreciation of the disclosed concepts can be gained from the following description of the preferred embodiments when read in connection with the accompanying drawings, in which:

fig. 1 is a partial cross-sectional view of a vacuum switching apparatus and electrical contacts thereof, according to a non-limiting embodiment of the disclosed concept.

Figure 2 is a top plan view of one of the electrical contacts of figure 1;

figure 3 is a bottom isometric view of the electrical contact of figure 2;

FIG. 4 is a cross-sectional view of the electrical contact of FIG. 2 taken along line A-A of FIG. 2;

FIG. 5 is a bottom isometric view of another electrical contact according to another non-limiting embodiment of the disclosed concept;

FIG. 6 is a bottom isometric view of another electrical contact according to another non-limiting embodiment of the disclosed concept; and is

Figure 7 is a bottom isometric view of another electrical contact according to another non-limiting embodiment of the disclosed concept.

Description of the preferred embodiments

As used herein, the term "number" shall mean one or more than one integer (i.e., a plurality).

As used herein, two or more parts are "connected" or

The statement that "coupled" together shall mean that the parts are joined together either directly or joined through one or more intermediate parts.

As used herein, the statement that two or more parts or components "engage" one another shall mean that the components contact one another and/or exert a force, either directly or through one or more intermediate parts or components.

As used herein, the term "trough-like portion" means a region, portion, or section of a structure (such as an electrical contact) in accordance with the concepts disclosed herein, where material has been removed or otherwise absent or has a reduced amount of material as compared to other regions, portions, or sections of the structure, and shall expressly include, but not be limited to, a slot, thinned portion, blind hole, void, hollow space, groove, or any suitable number and configuration of combinations of the foregoing.

Fig. 1 shows a vacuum switching apparatus (e.g., without limitation, a vacuum circuit breaker 2) including a tubular ceramic member 4, a tubular vapor shield 6 located inside the ceramic member 4, and a pair of separable

electrical contacts

100, 200 located inside the vapor shield 6. The

electrical contacts

100, 200 are spiral contacts that are structured to engage and disengage from each other in order to close and open the vacuum interrupter 2. Figure 2 illustrates a top plan view of the power contact 100. As shown, the electrical contact 100 includes a central portion 102 and a plurality of

petal portions

110, 130, 150, 170 extending from the central portion 102. As will be discussed in greater detail below, the electrical contact 100 provides a number of novel advantages for the vacuum interrupter 2 as compared to prior art electrical contacts (not shown). Among other benefits, the

petal portions

110, 130, 150, 170 of the electrical contact 100 have a significantly reduced likelihood of opening during operation of the vacuum interrupter 2 as compared to prior art electrical contacts (not shown). In addition, the power contact 100 advantageously increases current interruption capability by forcing more current to the arc surface and conducting heat away from the arc root. In one non-limiting embodiment of the disclosed concept, the 200 electrical contacts (fig. 1) are configured as a mirror image of the electrical contacts 100. However, for ease of disclosure, only the power contact 100 will be described in detail herein. It should be appreciated that one or both of the

power contacts

100, 200 may include any known or suitable slot or combination of slots in accordance with the concepts disclosed herein.

With continued reference to fig. 2, each of the

petal sections

110, 130, 150, 170 includes a respective

first surface

112, 132, 152, 172. When mounted in the vacuum interrupter 2, the

first surfaces

112, 132, 152, 172 face in a direction towards the electrical contact 200 and move into and out of engagement with the electrical contact 200 to close and open the vacuum interrupter 2. Because the vacuum interrupter 2 is subjected to relatively high forces associated with the closing and opening of the

electrical contacts

100, 200, it is desirable that the

electrical contacts

100, 200 be able to withstand the impact energy associated with such closing and opening. To achieve this, the

petal sections

110, 130, 150, 170 each have a novel geometry, as shown more clearly in fig. 3 and 4.

Figure 3 illustrates a bottom isometric view of the power contact 100. As shown, each of the

petal portions

110, 130, 150, 170 also has a respective

second surface

114, 134, 154, 174 extending from the central portion 102. It should be appreciated that the

second surfaces

114, 134, 154, 174 each face in a second direction that is generally opposite the direction in which the

first surfaces

112, 132, 152, 172 face. The

petal portions

110, 130, 150, 170 each have a trough-

like portion

116, 136, 156, 176 extending inwardly from the respective

second surface

114, 134, 154, 174 toward the respective

first surface

112, 132, 152, 172. In other words, each of the

petal sections

110, 130, 150, 170 has a void or hollowed-out area on its rear portion (i.e., the portion facing away from the opposing electrical contact 200 (fig. 2.) the trough-shaped

sections

116, 136, 156, 176 each have a respective

third surface

118, 138, 158, 178 and a respective

fourth surface

120, 140, 160, 180 extending from the

third surface

118, 138, 158, 178, hi the present exemplary embodiment, the

third surfaces

118, 138, 158, 178 are perpendicular to the

fourth surfaces

120, 140, 160, 180, and extend inwardly from the

second surfaces

114, 134, 154, 174 it should be appreciated, therefore, that the trough-

like portions

116, 136, 156, 176 can be machined by a relatively simple milling operation it should also be appreciated that the electrical contact 100 or a similar suitable alternative electrical contact (e.g., without limitation, an electrical contact in which the third surface is not perpendicular to the fourth surface, not shown) can be cast or formed such that additional machining of the trough-like portions is not required.

Figure 4 shows a cross-sectional view of the power contact 100. For ease of disclosure, only the petal section 130 will be discussed in detail, but it should be understood that the

petal sections

110, 150, 170 are identical in structure and function to the petal section 130. The first surface 132 lies in a plane 133 and the fourth surface 140 lies in another plane 141 parallel to the plane 133. Plane 141 is also located between plane 133 and second surface 134. In one embodiment, plane 141 is located approximately midway between plane 133 and second surface 134. The second surface 134 is spaced from the plane 133. The third surface 138 is positioned perpendicular to the plane 133. As a result, the trough portion 136 extends a considerable distance into the interior of the power contact 100, thereby substantially reducing the mass of the power contact 100, as compared to prior art power contacts (not shown). Referring again to fig. 3, each of the

petal sections

110, 130, 150, 170 has a respective

distal portion

122, 142, 162, 182 positioned opposite the central portion 102. In the present exemplary embodiment, each respective

fourth surface

120, 140, 160, 180 extends from proximate the central portion 102 to proximate the respective

distal portion

122, 142, 162, 182, thereby further reducing the mass of the electrical contact 100.

As described above, the electrical contact 100 provides a novel mechanism to significantly reduce the likelihood of the

lobe portions

110, 130, 150, 170 breaking away from the central portion 102 during operation of the vacuum interrupter 2 (fig. 1). More specifically, by having a reduced mass, the power contact 100 moves with less momentum (i.e., momentum equals mass times velocity) than prior art power contacts (not shown). Thus, when the power contact 100 changes direction, either by striking the power contact during closing or by moving away from the power contact during opening, the oscillation of the power contact 100 will be significantly less than the higher mass power contacts (not shown) of the prior art. Thus, the likelihood of breakage of the

petal sections

110, 130, 150, 170 caused by such oscillation is advantageously reduced. Accordingly, the life of the power contact 100 can be extended as compared to prior art power contacts (not shown) because the power contact will move in a relatively fixed position.

Furthermore, due to the new trough-

like portions

116, 136, 156, 176, the mass of the electrical contact 100 is more concentrated on the arcing surfaces (i.e., the portions from which the

first surfaces

112, 132, 152, 172 and the

lobe portions

110, 130, 150, 170 extend to the

distal portions

122, 142, 162, 182), it must be observed that current flows from the central portion 102 to the

distal portions

122, 142, 162, 182, wherein during a current interruption, the roots of the running arc columns will likewise be concentrated toward the arcing surfaces (i.e., the portions from which the

first surfaces

112, 132, 152, 172 and the

lobe portions

110, 130, 150, 170 extend to the

distal portions

122, 142, 162, 182). This enhances the transverse magnetic field driving the rotation of the column arc and increases the interrupting performance of the vacuum interrupter 2 (fig. 1). In addition, because the electrical contact 100 has a reduced mass in the

petal sections

110, 130, 150, 170, heat is advantageously conducted away from the arcing surfaces (i.e., the

first surfaces

112, 132, 152, 172 and the portions of the

petal sections

110, 130, 150, 170 from which they extend to the

distal end portions

122, 142, 162, 182) in a shorter time.

Fig. 5 and 6 illustrate other

electrical contacts

300, 400 of different slot designs in accordance with the concepts disclosed herein, each of which may be substituted for either or both of the electrical contacts 100, 200 (fig. 1) and/or substituted into the vacuum interrupter 2 (fig. 1) in any suitable combination. As shown, each of the

electrical contacts

300, 400 has a respective

central portion

302, 402 and a respective plurality of petal portions (only petal

portions

310, 410 are numbered) extending from the

central portion

302, 402. The

petal sections

310, 410 have opposite

respective end portions

311, 313, 411, 413 and

respective midpoints

315, 415 between the

end portions

311, 313, 411, 413. The

first end portions

311, 411 extend from the respective

central portions

302, 402. Further, as shown, each of the

petal portions

310, 410 has a

respective trough portion

316, 416 located between a

respective midpoint

315, 415 and a respective

second end portion

313, 413. The function of the

trough portions

316, 416 is the same as the function of the

trough portions

116, 136, 156, 176 of the power contact 100 discussed above. However, by positioning the trough-

like portions

316, 416 between the

respective midpoints

315, 415 and the respective

second end portions

313, 413, the electrodes (see, e.g., electrode 8, shown in fig. 1) advantageously have a greater portion of the

electrical contacts

300, 400 mated therewith and thereby better secured.

Figure 7 illustrates another electrical contact 500 that may replace either of the electrical contacts 100, 200 (figure 1), according to another non-limiting embodiment of the disclosed concept. Is replaced into the vacuum interrupter 2 (fig. 1). As shown, the electrical contact 500 has a central portion 502 and a plurality of petal portions (only petal portion 510 is numbered) extending from the central portion 502. The petal portion 510 has a plurality of

trough portions

516, 524, 528, each of which extends inwardly from the second surface 514 toward the first surface (not shown in fig. 7). As shown, each of the trough-

like portions

516, 524, 528 has a respective

cylindrical surface

518, 525, 529 extending inwardly from the second surface 514 towards the first surface, and another respective surface (two of the three

surfaces

520, 526 are shown) extending from the

cylindrical surface

518, 525, 529. Thus, it should be appreciated that the trough portions (such as the

trough portions

516, 524, 528) can be relatively easily machined with conventional drill bits. It should also be appreciated that an electrical contact, such as the electrical contact 500, may have any suitable number of trough-like portions extending inwardly from the second surface of the petal sections without departing from the scope of the disclosed concept.

It should also be appreciated that the concepts disclosed herein of providing a trough-like portion on the rear side of an electrical contact may employ any suitable spiral-type transverse magnetic field electrical contact design and geometry, in addition to the

electrical contacts

100, 200, 300, 400, 500 described herein.

Accordingly, the disclosed concept provides improved (e.g., without limitation, better protection against petal cracking, better interruption of current flow, and heat dissipation from arcing surfaces) vacuum switching apparatus 2 and

electrical contacts

100, 200 thereof,

300. 400, 500, wherein the

petal sections

110, 130, 150, 170, 310, 410, 510 have a number of trough-

like portions

116, 136, 156, 176, 316, 416, 516, 524, 528 disposed therein. The trough-

like portions

116, 136, 156, 176, 316, 416, 516, 524, 528 advantageously reduce the overall mass of the

respective petal sections

110, 130, 150, 170, 310, preferably at the periphery thereof where oscillation is most likely to occur during opening and closing. In this way, the oscillations (the main cause of the cracks) of the

petal sections

110, 130, 150, 170, 310, 410, 510 are significantly reduced. Furthermore, since the

electrical contacts

100, 200, 300, 400, 500 have a reduced mass, heat will advantageously be conducted away from the arcing surfaces 112, 132, 152, 172 in a shorter time.

While specific embodiments of the disclosed concept have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the concepts disclosed which is to be given the full breadth of the claims appended and any and all equivalents thereof.

Claims

1. An electrical contact for a vacuum switching apparatus, the vacuum switching apparatus including a second electrical contact, the electrical contact comprising:

a central portion; and

a plurality of petal portions that each extend from the central portion, each of the plurality of petal portions including a first surface that faces in a first direction and is configured to engage the second electrical contact, and a second surface that faces in a second direction that is substantially opposite the first direction,

wherein at least one of the plurality of petal portions further has a trough portion extending inwardly from the second surface toward the first surface.

2. The electrical contact of claim 1, wherein the first surface is disposed in a plane; wherein the second surface is spaced from the plane; wherein the trough portion has a third surface extending inwardly from the second surface; and wherein the third surface is disposed perpendicular to the plane.

3. The electrical contact of claim 2, wherein the trough portion further has a fourth surface extending from the third surface; wherein the fourth surface is disposed in another plane; and wherein the further plane is disposed between the plane and the second surface.

4. The electrical contact of claim 3, wherein each of the plurality of petal sections further has a distal portion disposed opposite the central portion; and wherein the fourth surface extends from proximate the central portion to proximate the distal portion.

5. The electrical contact as recited in claim 3, wherein the other plane is disposed substantially midway between the plane and the second surface.

6. The electrical contact of claim 1, wherein the at least one of the plurality of petal portions is each of the plurality of petal portions.

7. The electrical contact of claim 1, wherein the at least one of the plurality of petal sections further has a first end section, a second end section disposed opposite the first end section, and a midpoint disposed between the first end section and the second end section; wherein the first end portion extends from the central portion; and wherein the trough portion is disposed generally between the midpoint and the second end portion.

8. The electrical contact as recited in claim 1, wherein the at least one of the plurality of lobe portions further has a plurality of other trough portions that each extend inwardly from the second surface toward the first surface.

9. The electrical contact as recited in claim 8, wherein the trough portion and the plurality of other trough portions each have a cylindrical surface that extends inwardly from the second surface toward the first surface.

10. A vacuum switching apparatus comprising:

the electrical contact of any one of claims 1 to 9; and

a second electrical contact.

11. The vacuum switching apparatus of claim 10, wherein the second electrical contact comprises:

a central portion, and

a plurality of petal portions that each extend from the central portion of the second electrical contact, each of the plurality of petal portions of the second electrical contact including a fifth surface that faces a third direction and is configured to engage the electrical contact and a sixth surface that faces a fourth direction opposite the third direction,

wherein at least one of the plurality of lobe portions of the second electrical contact further has a trough portion extending inwardly from the sixth surface toward the fifth surface.

12. The vacuum switching apparatus of claim 11, wherein the vacuum switching apparatus further comprises a tubular ceramic member and a tubular vapor cap disposed inside the tubular ceramic member; wherein the second electrical contact and the electrical contact are disposed inside the tubular vapor shield; wherein the vacuum switching apparatus is a vacuum interrupter.